JP2527914B2 - Smelting of non-ferrous sulfide - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dry smelting treatment of a non-ferrous sulfide raw material, and more particularly, to smelting or conversion of a granular non-ferrous sulfide raw material such as nickel sulfide or copper sulfide. In the method of the present invention, the granular sulfide raw material is charged below the surface of the molten metal in the reactor. Then, when an upper gas is blown in using an oxygen-containing gas, heat is generated and oxidation of the sulfide occurs in a state where the amount of dust generated is significantly reduced.

[0002]

2. Description of the Related Art One method for treating sulfide ore concentrates currently in use is to burn sulfur or iron in ore and suspend the concentrate in an oxidizing medium. Smelting or conversion. In this way, the furnace waste gas can be economically treated to recover a substantial portion of the liberated sulfur content. A significant disadvantage of the flash operation is that a significant amount of dust is generated, which must be removed by a gas scrubbing system prior to the sulfur dioxide recovery process. On the other hand, when the sulfide raw material is charged below the surface of the molten metal, the amount of dust generated is considerably reduced.

In self-smelting or conversion, the heat of combustion is generated on the freeboard of the furnace, and the refractory may be overheated.
In the method of the present invention utilizing the top blowing technique, heat is generated on the surface of the hot water away from the walls of the reactor. Embodiments of the present invention utilize non-reactive gas sparging as the bottom agitation mechanism. The heat is dispersed by stirring the hot water generated by the gas spray,
The temperature of the hot water becomes uniform. This significantly reduces refractory damage. Furthermore, the reactor used in the process of the present invention (usually the Pierce Smith converter type because of its ease of retrofitting) appears to have a higher specific capacity than the flash reactor.

The upper blowing step alone has its own drawbacks. That is, although the oxygen efficiency is high, the oxygen efficiency during the self-melting reaction is less than 100%. However, when the top blowing process was used with sulfide charging below the surface of the melt, it was surprisingly found that this unique process was superior to the self-melting reaction in terms of overall economics. . This is especially true when considering the issue of dust generation.
For example, in the processing of chalcocite, 15% or less of the supplied copper becomes dust at the end in the self-melting conversion. When chalcocite is added to the hot water, this amount is considerably reduced.

In the past, it has been proposed to carry out the solid charge below the surface of the melt in combination with the blowing of air or oxygen-enriched air into the melt. U.S. Patent No. 3, by Meissner
Although this prior art method taught by 281,236 reduces the dust produced by the self-melting reaction, it has serious drawbacks. That is, a lower level of oxygen enrichment requires more fuel, and a higher proportion of waste gas produced requires a larger and more expensive gas scrubbing system to handle it. A shroud tuyere would be required if top-blown oxygen was used in such a method. Furthermore, these methods are known to cause excessive refractory and tuyere wear.

"Blow top, bottom agitate" in the preferred embodiment, as compared to just blowing an oxygen containing gas.
It is desirable to use US Pat.
It was first disclosed by Marcuson et al. In the specification of 0,667 regarding the conversion of white metal copper. Further bottom agitation with top blowing and in-grain granules will further help solve the above problems. Bottom stirring promotes circulation of the melt and can increase contact with top blown oxygen. Therefore, the design of the lance and container is simplified, the cost is reduced and the reaction efficiency is increased.

[0007]

In the smelting or conversion process of the present invention, it is intended to charge a granular sulphide sulfide raw material such as nickel sulphide and / or copper sulphide into the melt. An oxygen-containing gas is blown into the molten metal from above. The molten metal may be stirred from below with a non-reactive gas such as nitrogen, if necessary.

Due to the action of the charging tuyere, the hot water is significantly stirred. The combination of this stirring action and the blowing of the oxygen-containing gas from above through the lance directed to the hot water eliminates the need for a consumable lance and a tuyere for the introduction of oxygen. This stirring can be further enhanced by sparging with a non-reactive gas from below. The present invention
By supplying oxygen from above while charging the sulfide raw material below the surface of the molten metal, the problem of tuyere wear due to oxygen charging can be overcome. The agitation caused by solids charging and optionally sparging with non-reactive gas agitates the melt so that it contacts the oxygen-containing gas at its surface. Furthermore, the problem of dust generation is greatly reduced as compared with the self-fluxing reaction caused by introducing granular sulfides into hot water.

In the method of the present invention, an improved tuyere injector particularly suitable for incorporating particulate sulfide into hot water is of the type described in Canadian Patent Application Publication No. 2,035,542. Is. Overall, the unique concept of combining the charge of granular sulphide raw material into the melt with the advantageous use of top blowing provides a clean, inexpensive and efficient conversion process. Furthermore, the new process can be advantageously carried out with a Pierce Smith rotary converter, which can be easily retrofitted with the required equipment.

[0010]

The present invention will be described below with reference to examples. Several tests were performed to show the effectiveness of the method of the invention. A separate experiment was completed during each test to sample and adjust the injector and burner.
Dry granular chalcocite with a nominal composition of 75% copper, 20% sulfur, 3% nickel was charged to a Pierce Smith converter reactor during a series of six tests. A seed melt consisting of approximately 137 tonnes of semi-blister was prepared in the reactor before each test.
An auxiliary oxygas burner was used to maintain the bath temperature during charging. Two tuyeres of the type described in Canadian Patent Publication No. 2,035,542 were placed 8 feet (2.4 m) from each end wall.

The charging speed from the two tuyere is 18.2
The range was 27.3 tons / hour. Use a portable compressor to deliver 120 transport air to the tuyere under the tank.
It was supplied at psi (828 kPa). This resulted in a tank pressure of 80-90 psi (552-621 kPa) and a tuyere pressure of 40 psi (276 kPa). Bottom agitation was achieved by sparging nitrogen through 5 perforated stoppers spaced along the bottom of the reactor shell.

For Test Nos. 1 to 4, a water-cooled oxygen lance also serving as the addition of natural gas was attached at an angle of 45 ° through the end face of the reactor shell, and charged chalcopyrite was added as a semi-blister (sulfur content: 4 %). As shown in Table 1, the samples confirmed the presence of the semi-blister bath at the end of each charging time.

[0013]

[Table 1]

Comparative Test Nos. 5-6 show that oxygen injection affects fuel consumption and smelting results. In these tests, no oxygen was fed into the reactor through the lance and the available oxygen sources for the reaction were the air carried by the feed and oxygen permeating through the converter port. A secondary oxygas burner was required to maintain the temperature due to the lack of oxygen bubbling and the heat loss generated by the reduction of the sulfide reaction. As shown in Table 2, sulfur at a high concentration (from 11.47 to 12.25%), it remained at the top of the bath at the end of the cycle in the form of a white metal (Cu ₂ S). These test No. In the two tests of 5 and 6, only one tuyere was operated, and the charging speed was the test No.
However, the natural gas flow rate was almost the same.

[0015]

[Table 2]

The amount of dust in the offgas from the reactor was measured during the two charging periods. Adding the amount of dust trapped in the flue to this value resulted in a 1% dust loss. When the same test was performed in a flash converter, the dust loss was 5%. Although these numbers are rough comparisons, they show that the method of the present invention has significant environmental advantages.

It is also clear that the method of the invention can be extended to the treatment of nickel sulfide and other non-ferrous sulfides such as iron-containing nickel sulfide and / or copper sulfide.
In the case of iron-containing non-ferrous sulfide, slag is generated on the surface of the molten metal, and therefore an additional step is required. The formation of slag can give rise to two separate but related problems. If the slag layer is too thick, it will interfere with the conversion process by interfering with the interaction of the molten non-ferrous sulfide in the melt with the top-blown oxygen. In addition, excessively thick slag can result in unwanted excessive splash.
May occur. The thickness of the slag layer must be controlled by either continuously overflowing the slag or by frequently tapping or casting the slag out of the reactor.

A second problem with slag formation is that as the conversion process progresses and becomes more and more oxidized, magnetite is formed and the slag becomes thick and non-fluid. In the case of copper sulfide treatment, addition of lime flux is advantageous for maintaining the fluidity of slag. In the case of treating nickel sulfide, the combined addition of lime and silica flux is effective.

[0019]

As described above, according to the present invention,
Smelting of non-ferrous sulfide raw material with low dust generation, low sulfur concentration, clean, economical and efficient by combination of charging granular sulfide raw material into molten metal and upper blowing of oxygen-containing gas Or it can be converted.

Claims (19)

(57) [Claims] 1. A step of preparing a molten sulfide raw material in a reactor, a step of charging a granular sulfide raw material below the surface of the molten metal, and a step of blowing an oxygen-containing gas into the molten metal. A method for smelting or converting a granular non-ferrous sulfide raw material characterized by: 2. The method according to claim 1, wherein the non-ferrous sulfide raw material is nickel sulfide and / or copper sulfide. 3. The method according to claim 1, wherein the molten metal to be prepared is a seed molten metal containing smelted or converted sulfide raw material. 4. Method according to claim 1, characterized in that the upper blowing is carried out via a lance protruding above the melt. 5. The method according to claim 1, wherein the oxygen-containing gas is oxygen. 6. The method according to claim 1, wherein the granular sulfide raw material is charged through one or more tuyere located below the surface of the molten metal. 7. The method of claim 1, further comprising the step of bottom stirring the melt with a non-reactive gas. 8. A process according to claim 7, characterized in that the bottom stirring is carried out via one or more perforated stoppers located along the bottom of the reactor. 9. The method of claim 7, wherein the non-reactive gas is nitrogen. 10. A step of preparing a molten metal of a sulfide raw material in a reactor, a step of charging a granular sulfide raw material below the surface of the molten metal, a step of blowing an oxygen-containing gas into the molten metal, And a step of preventing the iron-containing slag layer from interfering with the smelting or conversion reaction, the method for smelting or converting a granular non-ferrous sulfide raw material. 11. The method according to claim 10, wherein the non-ferrous sulfide raw material is nickel sulfide and / or copper sulfide. 12. The method according to claim 10, wherein the prepared molten metal is a seed molten metal containing a smelted or converted sulfide raw material. 13. The method according to claim 10, wherein the upper blowing is carried out via a lance protruding above the molten metal. 14. The method according to claim 10, wherein the oxygen-containing gas is oxygen. 15. The method according to claim 10, wherein the granular sulfide raw material is charged through one or more tuyere located below the surface of the molten metal. 16. The thickness of the slag layer is maintained by removing the slag continuously or periodically so that the slag layer does not interfere with the smelting or conversion reaction. the method of. 17. The method according to claim 10, further comprising the step of agitating the molten metal at the bottom with a non-reactive gas.
The method described in. 18. The method according to claim 17, wherein the bottom stirring is carried out via one or more perforated stoppers located along the bottom of the reactor. 19. The method of claim 17, wherein the non-reactive gas is nitrogen.